Problem: Simplify the following expression: $k = \dfrac{30f}{20h + 5} - \dfrac{10g}{20h + 5}$ You can assume $f,g,h \neq 0$.
Solution: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{30f - (10g)}{20h + 5}$ $k = \dfrac{30f - 10g}{20h + 5}$ The numerator and denominator have a common factor of $5$, so we can simplify $k = \dfrac{6f - 2g}{4h + 1}$